It may still be years way before humans can live and produce offspring Mars. But there’s new hope for a future on the red planet now that a new study has found that some microscopic organisms, like fungi and bacteria, are able to survive a long time (up to years) in a vacuum without any technological assistance.
Does it mean that scientists could in some way “plant” certain types of microorganisms in outer space and initiate life there? After all, that’s part of the grand idea of interplanetary colonization that entrepreneurs like Elon Musk have poured money into.
In the science community, this theory is known as panspermia. To find out how feasible it might be, a group of Japanese researchers in 2015 sent several packs of dried cell pellets of Deinococcus, a highly radiation-resistant bacterium, to the International Space Station and stuck them on the outside of the lab, leaving them exposed to the harsh vacuum of space. The microbial cell pellets were attached to the Japan Aerospace Exploration Agency’s Experiment Handrail Attachment Mechanism (ExHAM).
The experiment, officially called Tanpopo (meaning “dandelion” in Japanese), went on for three years, with scientists checking the condition of the bacteria at the end of each year, and concluded in 2018.
After two more years of data analysis, researchers led by Akihiko Yamagishi, an astrobiologist at the Tokyo University of Pharmacy and Life Science, published their findings this week in the journal Frontiers in Microbiology.
The scientists found that the thicker the cell pellets are, the better they can survive damage from UV radiation in space. Based on lab results, cell pellets with a diameter larger than 1 millimeter can stay alive in the space environment for two to eight years. That’s enough time for manmade spacecraft to travel from Earth to another planet.
“Deinococcal cell pellets in the sub-millimeter range would be sufficient to allow survival during an interplanetary journey from Earth to Mars or Mars to Earth,” which takes several months in the shortest orbit, says the study. “Cell pellets of 1,000 μm diameter would be able to survive the shortest travel time in space.”
There are still a few problems to be worked out, though. For instance, a microbial cell needs to survive all stages of an interplanetary flight, including exiting Earth’s atmosphere and entering another planet’s atmosphere, which is usually the most dangerous part of a space journey.
Yamagishi’s team says they will have to conduct more space exposure experiments with different species under different conditions to see how realistic mass panspermia is and at what scale the process can be carried out.